Random number generation device having a ring oscillator

• US 8,805,907 B2
• Filed: 09/17/2008
• Issued: 08/12/2014
• Est. Priority Date: 01/08/2008
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ikegami, Kazutaka, Yasuda, Shinichi
• Primary Examiner(s): Bullock, Jr., Lewis A
• Assistant Examiner(s): Dang, Christine
• Application Number:
  US12/212,205
• Publication Number:
  US 20090177725A1
• Time in Patent Office: 2,155 Days
• Field of Search: None
• US Class Current: 708/251
• CPC Class Codes: G06F 7/588 Random number generators, i.e. based on natural stochastic processes
• CPC Class Codes: H03K 3/0315 Ring oscillators
• CPC Class Codes: H03K 3/84 Generating pulses having a predetermined statistical distribution of a parameter, e.g. random pulse generators

Abstract

It is made possible to provide a random number generation device which generates a physical random number with as little power dissipation as possible. A random number generation device includes: a ring oscillator having at least one set, each set comprising a current noise source and a Schmitt inverter configured to receive an output of the current noise source; and a conversion circuit configured to convert output frequency fluctuation of the ring oscillator to a random number and output the random number.

Claims

1. A random number generation device comprising:

a ring oscillator having at least one set of components, each set of components comprising a current noise source, a Schmitt inverter configured to receive an output of the current noise source, and at least two inverters which are connected in series to the output of the Schmitt inverter, wherein an output of a last inverter of the at least two inverters is input to the current noise source, the current noise source being an n-channel MOSFET type current noise source including a source electrode, a drain electrode, and a gate electrode, current flowing between the source electrode and the drain electrode fluctuating when constant voltages are applied to the source electrode, the drain electrode, and the gate electrode respectively; and

a conversion circuit configured to convert an output of the Schmitt inverter to a random number and output the random number.

2. The device according to claim 1, wherein the Schmitt inverter has a first threshold voltage V_H and a second threshold voltage V_L smaller than the first threshold voltage V_H, and

the first threshold voltage V_H and the second threshold voltage V_L satisfy the following relation expression,

3. The device according to claim 1, wherein

a voltage VG applied to a gate of the n-channel MOSFET type current noise source is given so as to satisfy

VG>

V_H+Vth

where V_H is a threshold voltage of the Schmitt inverter that output voltage of the Schmitt inverter changes from high-level to low-level when input voltage of the Schmitt inverter exceeds V_H, and Vth is a threshold of the n-channel MOSFET type current noise source.

5. The device according to claim 1, wherein the conversion number circuit comprises a D-type flip-flop having a D terminal to receive an output of the ring oscillator, a CK terminal to receive an external oscillation signal, and a Q terminal to output the random number.

6. The device according to claim 1, wherein the Schmitt inverter comprises:

an input terminal;

an output terminal;

a first p-channel MOSFET having a gate connected to the input terminal and having a source connected to a drive power supply;

a second p-channel MOSFET having a gate connected to the input terminal, having a source connected to a drain of the first p-channel MOSFET, and having a drain connected to the output terminal;

a first n-channel MOSFET having a gate connected to the input terminal and having a drain connected to the drain of the second p-channel MOSFET;

a second n-channel MOSFET having a gate connected to the input terminal, having a drain connected to a source of the first n-channel MOSFET, and having a source connected to ground;

a third p-channel MOSFET having a source connected to the drain of the first p-channel MOSFET, having a drain connected to the ground, and having a gate connected to the output terminal; and

a third n-channel MOSFET having a source connected to the source of the first n-channel MOSFET, having a drain connected to the drive power supply, and having a gate connected to the output terminal.

7. The device according to claim 1, wherein the ring oscillator is a series circuit obtained by serially connecting an odd number of sets each comprising the current noise source and the Schmitt inverter.

8. The device according to claim 1,

a sum of the number of the Schmitt inverters and the number of the inverters is an odd number.

4. A random number generation device comprising:

a ring oscillator having at least one set of components, each set of components comprising a current noise source, a Schmitt inverter configured to receive an output of the current noise source, and at least two inverters which are connected in series to the output of the Schmitt inverter, wherein an output of a last inverter of the at least two inverters is input to the current noise source, the current noise source being an p-channel MOSFET type current noise source including a source electrode, a drain electrode, and a gate electrode, current flowing between the source electrode and the drain electrode fluctuating when constant voltages are applied to the source electrode, the drain electrode, and the gate electrode respectively; and

a conversion circuit configured to convert an output of the Schmitt inverter to a random number and output the random number.

9. The device according to claim 4, wherein

a voltage VG applied to a gate of the p-channel MOSFET type current noise source is given so as to satisfy

VG<

V_L−

Vth

where V_L is a threshold voltage of the Schmitt inverter that output voltage of the Schmitt inverter changes from low-level to high-level when input voltage of the Schmitt inverter lowers V_L, and Vth is an absolute value of a threshold of the p-channel MOSFET type current noise source.

10. The device according to claim 4, wherein

the Schmitt inverter has a first threshold voltage VH and a second threshold voltage VL smaller than the first threshold voltage VH, and

the first threshold voltage VH and the second threshold voltage VL satisfy the following relation expression,

11. The device according to claim 4, wherein the conversion number circuit comprises a D-type flip-flop having a D terminal to receive an output of the ring oscillator, a CK terminal to receive an external oscillation signal, and a Q terminal to output the random number.

12. The device according to claim 4, wherein the Schmitt inverter comprises:

an input terminal;

an output terminal;

a first p-channel MOSFET having a gate connected to the input terminal and having a source connected to a drive power supply;

a second p-channel MOSFET having a gate connected to the input terminal, having a source connected to a drain of the first p-channel MOSFET, and having a drain connected to the output terminal;

a first n-channel MOSFET having a gate connected to the input terminal and having a drain connected to the drain of the second p-channel MOSFET;

a second n-channel MOSFET having a gate connected to the input terminal, having a drain connected to a source of the first n-channel MOSFET, and having a source connected to ground;

a third p-channel MOSFET having a source connected to the drain of the first p-channel MOSFET, having a drain connected to the ground, and having a gate connected to the output terminal; and

a third n-channel MOSFET having a source connected to the source of the first n-channel MOSFET, having a drain connected to the drive power supply, and having a gate connected to the output terminal.

13. The device according to claim 4, wherein the ring oscillator is a series circuit obtained by serially connecting an odd number of sets each comprising the current noise source and the Schmitt inverter.

14. The device according to claim 4, wherein

a sum of the number of the Schmitt inverters and the number of the inverters is an odd number.